All Synchro Gearbox ratios

Would someone be kind enough to look up the ratios for the later 3.4 S-type and the 420. After the Jaguar all-sychro data not the earlier Moss

From my Jaguar Service Bulletin dated December 1964 for the introduction of the full syncho gearbox. Do not know if the 3.4, 3.8 and 4.2 units varied or not.
1st 2.933
2nd 1.905
3rd 1.389
4th 1.00
Rev. 3.378

Figures for the 420 I have are:
For the 240 I have
These are from road test data, so maybe not as reliable as John’s reply? I think you can safely assume 2.4 (240) used different ratios, however. Looks like S Type and 420 and probably bigger Mk2s were the same

The 240 ratios sound like a Moss box


The following gear ratio data is directly taken from the following publications: -

Jaguar Cars Ltd. Mark 2 Models, 2,4, 3.4, 3.8, 240 & 340. Service Manual No E121

Jaguar Cars Ltd. S Type 3.4 & 3.8 Service Manual 1963-1968 No E133/3.

These two manuals show ratios for the all syncro gearbox to be IDENTICAL for all the models covered, as below:-

1st Gear 3.04:1

2nd Gear 1.973:1

3rd Gear 1.328:1

4th Gear 1.00:1

Reverse 3.49:1

On a mass production standard road car there is no reason why gear ratios should be changed across similar range cars. Like many producers Jaguar accommodated varying engine sizes by changing the axle ratios.



thanks very much for that norman

GEARSET - ALL SYN.pdf (268.8 KB)

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I think it’s possible they had a different set of ratios to suit the different torque characteristics of the 2.4. The others were all vaguely similar . Several sets of ratios were available for the Moss box back in the 50’s dependent on vehicle ( ie sports or saloon , close ratio, normal ratio etc.)

Thanks Norman
Excellent document